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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8370
Experience:  Furnace, A/C and heat pump specialist.
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Temps in Arkansas are bouncing between needing heat or A/C.

Customer Question

Temps in Arkansas are bouncing between needing heat or A/C. For a day or two, we have been leaving the system off with fan on for air circulation during the day.
This morning, we turned on the heat and the furnace fired up but the blower fan would never come on. It clicked and attempted to come on, but only caused lights on the same circuit to dim every second or two until the furnace kicked off. Does the same thing now in fan only mode (No heat or A/C on).
I checked out the board visually with nothing obviously wrong (I replaced the board about two years ago with a Honeywell OEM board). Fan spins freely. I then replaced the capacitor with the same results.
I then pulled the three wires on the motor and probing bot***** ***** to top red and to middle other color and got 1.4 to 1.7 ohms. The next to the top slot was empty.
I then turned power switch on with panel open. I put my foot on the door safety switch and the motor tried to start again (fan turned some even after I took my foot off). Then, I held the switch down again and after an attempt or two, the blower fan kicked on ... but about 5 seconds after starting, it blew the breaker.
Any suggestions?
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

If blower made breaker trip it sounds like there is a short in the motor windings